¿Qué tal
SELECT *
FROM team t
JOIN team_user tu ON (tu.id_team = t.id)
GROUP BY t.id
HAVING (SUM(tu.id_user IN (1,5)) = 2) AND (SUM(tu.id_user NOT IN (1,5)) = 0)
Estoy asumiendo un índice único en team_user (id_team, id_user).
¿Qué tal
SELECT *
FROM team t
JOIN team_user tu ON (tu.id_team = t.id)
GROUP BY t.id
HAVING (SUM(tu.id_user IN (1,5)) = 2) AND (SUM(tu.id_user NOT IN (1,5)) = 0)
Estoy asumiendo un índice único en team_user (id_team, id_user).